University of Amsterdam Master System and Network Engineering Research Project 2 Functional breakdown of decentralised social networks Student: Supervisor: Wouter Miltenburg Michiel Leenaars [email protected] [email protected] July 6, 2015 Abstract Current centralised social networks are used by a huge number of users for a variety of reasons. With Facebook, Google+, LinkedIn, or Twitter, users are not in control of their own data and access control is centralised and proprietary. Decentralised social networks could be a solution to these problems and gives the control of the data back to users. This research is focused on the question which of the decentralised social networks is currently most suited to be provided as a service by hosting providers. This paper will therefore provide information about the current implementations, the protocols used by the various implementations, and will give a functional breakdown of the various decentralised social networks. Various implementations have been analysed, namely diaspora*, Friendica, GNU social, pump.io, and RedMatrix. The paper also describes the set of standards and protocols used by the various implementations. As most implementations use their own protocol, or implement the standards slightly differently, there is no interoperability without the use of extra plugins or enabling certain features. While there are a lot of standards for facilitating the message exchange, there are however standards missing that would make interoperability possible, which is described in this paper as well. RedMatrix is currently most suited to be provided as an alternative to the current centralised social networks and that can be provided as a service by hosting providers. It has an efficient message distribution model, enhanced privacy features, and provides an unique feature named nomadic identities. A list of recommendations and future work is included in this report as well. Contents 1 Introduction 2 1.1 Related Work . .2 1.2 Research Questions . .3 1.3 Approach and Methods . .4 2 Theory 6 2.1 Social networks and its users . .6 2.2 Protocols . .7 2.3 Features . 14 3 Analysis 16 3.1 Introduction of the implementations . 16 3.2 Functional breakdown . 20 3.3 Implementations with a different approach . 34 3.4 Use cases . 35 3.5 Standardisation . 37 3.6 Solution for hosting providers . 38 4 Conclusion 40 5 Recommendations 42 5.1 Permanent usernames . 42 5.2 Message distribution . 43 6 Future work 45 6.1 Deadlock . 45 6.2 Security . 45 6.3 Benchmark . 46 6.4 Stale data and accounts . 46 6.5 Proof of concept of suggestions . 46 References 47 A Projects not considered in scope 52 1 Chapter 1 Introduction Social networks like Facebook, Google+, LinkedIn, or Twitter are used by a huge number of people for a variety of reasons. People want to stay in contact with each other, stay updated about what is happening around them, or are reaching out for help. Inside a commercial (or in fact any third party) social network, users are not in control of their own data, and access control is centralised and proprietary. Facebook's network and its back end might well be a whole distributed infrastructure but it is considered as a black box from a user's or developer's perspective. If there is an infrastructure or connectivity problem within a single company, the whole service can come to a grinding halt. Users do not have access to their data at that moment and when a service is discontinued or the user is no longer interesting, acceptable, or eligible as a customer for some reason all of the user's data is lost along with their connections to other people and organisations - in effect their entire social graph. However, there is a solution for this problem by transforming the social network landscape from a centralised model to a decentralised one. This research started with the question on which implementation of a distributed social network can be included in the ARPA2 project [23]. The ARPA2 project wants to bring modern and secure Internet technology to end-users by providing a hosting platform that can be installed by a variety of hosting companies. If this hosting platform is adopted by hosting providers it can be offered as a solution to a great number of users. This research will focus on the features that are currently made available by various in- dependent projects. Which of them are mature enough, which of them are scalable, what kind of open protocols are used such that interoperability can exist between installations or other types of services, and what kind of non existing standards are currently limiting the development of these decentralised social networks. 1.1 Related Work Daniel R. Sandler and Dan S. Wallach propose the FETHR system [48] that connects micropublishers in a single global network. It describes what kind of users really make an impact on the workload of the overall system and also describes the lightweight HTTP- based protocol that is used to gossip new messages among subscribers. 2 Quite some research has already been done in P2P systems for social networks. Cuckoo by Xu et al. [57, 58] proposes an overlay network for providing a scalable and reliable microblogging service. This is done whilst offloading the traffic in its own P2P system, such that the Twitter servers conserve their bandwidth and processing power. There is also Litter by Juste et al. [35] that makes use of already existing peer-to-peer technologies and the paper describes Litter's implementation of sending and receiving messages. T. Perfitt and B. Englert propose Megaphone [43], a secure microblogging system that makes use of user certificates and where the network is arranged based on these certificates. Thiel et al. [54] already looked at the decentralised networks that exist and which are suitable based on a requirements driven approach. However, this research only looked at a few implementations and did not cover everything that will be researched in this project. The aforementioned research was of great help when we analysed the existing decentralised social networks. It gave us an idea how messages can be distributed inside a network, although most of the mentioned papers are about peer to peer systems, some of the solutions could be implemented in a non peer to peer system as well. The paper by Thiel et al. gave us an idea how we could analyse the existing decentralised social networks. Other papers that are of relevance to this research, and which have been used throughout this project, will be referenced accordingly in this paper. 1.2 Research Questions The research is formed around the main question shown below. What current implementation of a social decentralised network could be considered as an alternative to the current centralised social networks and could be offered as a service by hosting providers? As a result of the main question, shown above, there are the following sub questions. • Which functionalities exist in the typical social networks that we know nowadays? • Which alternative open source projects are available that are mature enough and which provide these functionalities in a decentralised model? • How do these different alternative open source projects differ from each other in a practical sense (e.g. security, standardisation, ID re-use, and scalability)? • Which implementation is most suited to create a decentralised social network that can be provided as a service by hosting providers? 3 1.3 Approach and Methods This research project mostly applied theoretical research. We have first analysed some existing large centralised social networks (i.e. Facebook, Google+, LinkedIn and Twitter) and made a list of features that are supported by these social networks. From this list we have created a list of basic features that must be supported by the implementations. After this had been done we made an inventory of the implementations that existed. Only the implementations that provided the basic feature set were considered an option along with some other requirements. After this had been done the features were analysed that are implemented by the different decentralised social network solutions. This also involved analysing the protocols that are used in the systems to see if interoperability can be ob- tained between the different solutions. Another aspect of the systems that was researched, is if the solutions can be scaled. To be able to answer all of this, a test setup was made that ran all of the analysed implementations. During the analysis of the implementations, we have also looked at the network traffic to get a better understanding of intercommunication between nodes. After we analysed the implementations, it was possible to see the limita- tions of the different implementations and we were able to conclude that indeed distributed social networks may realistically be provisioned through hosting providers. We identified a number of possible candidates and one implementation, at that moment, seemed to be most suited to be provided as an alternative to the current centralised social networks. Recommendations and suggestions were also included in this report if some limitations were observed or to improve the overall functionality of an implementation. 1.3.1 Use cases We started by creating a number of use cases that should be supported by the distributed social networks. These use cases have been made up during the research and are based on other use cases that have been used in previous research, which will be outlined in Section 2.1. The use cases are general enough such that they are applicable to real life scenarios, general enough to cover a range of different use cases that are similar to the ones mentioned in this report, and are used during the analyses of the implementations.